Relationship between the Hawaiian bobtail squid Euprymna scolopes and the bioluminescent bacteria Aliivibrio fischeri
Introduction
Many organisms on Earth maintain a mutualistic symbiotic relationship, where they live and even benefit from one another. A mutual assistance and association with a particular type of bacteria is required in many animals (Nardon, 1991). Many studies performed with gnotobiotic animals have disclosed that a host fails to grow and develop without the essential nutrients provided by their symbionts, and also that the bacteria takes part in the maturation of the organism in which they are associated with (Gordon, 1971). Recent studies show that light organ relationship between the Hawaiian bobtails squid Euprymna scolopes …show more content…
The A. fischeri gram-negative bacterial cells are found in the environments where E. scolopes hatchlings are exposed. The bacteria are found to accumulate in the crypts of the Hawaiian bobtail squid, suggesting their binding relationship to the mucus produced by it (Nyholm, 2003). After just one hour of hatching non-symbiotic bacteria is acquired in the light organ crypt and after two hours the bacterial cells are not able to enter anymore. When the gram-negative bioluminescence bacteria is in contact with the E. scolopes, the external ciliated epithelium of the light organ starts to release mucus for a period of forty-eight hours throughout the course of the colonization of A. fischeri is terminated. The termination of the mucus shows a secure strong bond between the Hawaiian bobtail squid E. scolopes and the bioluminescence bacteria A. fischeri (Nyholm, …show more content…
scolopes contain a higher density of bacteria. However, they discharge about 95% of the bacteria at the first appearance of light in the sky after they enter a period of inactivity by burying themselves in the sand. During this dormant state, whatever was left from the previous set of bacteria repopulates the crypts of the light organ in E. scolopes by nighttime.
E. scolopes are able to regulate the A. fischeri population by using the venting mechanisms. This mechanism also allows for later generations of both, A. fischeri and E. scolopes, to be colonized (Schleicher, T. R., & Nyholm, S. V. 2011).
Developmental changes in both organisms Once the relationship between E. scolopes and A. fischeri is secure various physiological changes occur in each organism. During the first couple hours that A. fischeri enters the host their flagella is lost. In the crypts of E. scolopes a molecule known ad VAI-1 is present which causes the bacterial cells to increase their illumination (Ruby, 1999). The Hawaiian bobtail squid as well as the bioluminescence bacteria is subjected to a morphological change where it loses the ciliated appendages located in both sides of the light organ (Wollenberg, 2012).